Link failure when building UML on linux-6.1.y after LLVM commit ec92d74a0ef89 #1982

nathanchance · 2024-01-17T21:52:29Z

After llvm/llvm-project@ec92d74 (according to my bisect), I see several modpost warnings then an error when building UML on linux-6.1.y (ARCH=um has -mcmodel=large as a result of 12783aa):

$ make -skj"$(nproc)" ARCH=um LLVM=1 mrproper defconfig linux
...
WARNING: modpost: vmlinux.o(__ex_table+0x0): Section mismatch in reference from the (unknown reference) (unknown) to the (unknown reference) .ltext:(unknown)
The relocation at __ex_table+0x0 references
section ".ltext" which is not in the list of
authorized sections.  If you're adding a new section
and/or if this reference is valid, add ".ltext" to the
list of authorized sections to jump to on fault.
This can be achieved by adding ".ltext" to
OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.
WARNING: modpost: vmlinux.o(__ex_table+0x4): Section mismatch in reference from the (unknown reference) (unknown) to the (unknown reference) .ltext:(unknown)
The relocation at __ex_table+0x4 references
section ".ltext" which is not in the list of
authorized sections.  If you're adding a new section
and/or if this reference is valid, add ".ltext" to the
list of authorized sections to jump to on fault.
This can be achieved by adding ".ltext" to
OTHER_TEXT_SECTIONS in scripts/mod/modpost.c.
...
/usr/sbin/ld: init/calibrate.o: relocation R_X86_64_32 against `.data' can not be used when making a PIE object; recompile with -fPIE
/usr/sbin/ld: failed to set dynamic section sizes: bad value
clang: error: linker command failed with exit code 1 (use -v to see invocation)
make[3]: *** [scripts/Makefile.vmlinux:34: vmlinux] Error 1
...

git bisect log

# bad: [f1156fb622a73bcf1623c9bebfb6a638b097af14] [AMDGPU][IGLP]: Add SchedGroupMask::TRANS (#75416)
# good: [065796bb9293b222fa3d63311af542a98b96d09a] [clang][OpenMP] Fix missing DI for __kmpc_global_thread_num (#73856)
git bisect start 'f1156fb622a73bcf1623c9bebfb6a638b097af14' '065796bb9293b222fa3d63311af542a98b96d09a'
# good: [774295ca1d5ff752cb478b61f22a5b1dbe33074f] [libc++][test] Fix MSVC warnings with `static_cast`s (#74962)
git bisect good 774295ca1d5ff752cb478b61f22a5b1dbe33074f
# good: [2ab926d959613e677458a818e9e42344ab4fd8c2] [flang][MLIR][OpenMP] Add support for `target update` directive. (#75047)
git bisect good 2ab926d959613e677458a818e9e42344ab4fd8c2
# bad: [a3952b4f022ce03c778ecc3b44ffff350b512735] [Analysis] Remove unused forward declarations (NFC)
git bisect bad a3952b4f022ce03c778ecc3b44ffff350b512735
# bad: [c1a6974d6b3dc7be2178d8db9f8fc6c2cc9230f2] [AMDGPU][MC] Add GFX12 SMEM encoding (#75215)
git bisect bad c1a6974d6b3dc7be2178d8db9f8fc6c2cc9230f2
# bad: [3194928c3cfa6623c5de78ae7ab2ab7ab0cf0232] [llvm-exegesis] Refactor MMAP platform-specific preprocessor directives (#75422)
git bisect bad 3194928c3cfa6623c5de78ae7ab2ab7ab0cf0232
# good: [1b531d54f6234488dec048fec1c5aca331bf8f3d] [InstrRef][nfc] Remove usage of unique_ptrs of arrays (#74203)
git bisect good 1b531d54f6234488dec048fec1c5aca331bf8f3d
# good: [5bc1adff69315dcef670e9fcbe04067b5d5963fb] Revert "lldb: Cache string hash during ConstString pool queries/insertions"
git bisect good 5bc1adff69315dcef670e9fcbe04067b5d5963fb
# bad: [0544c781728a665806b069cb8202acd4f6981a0a] Fix a crash from character type confusion interaction with libedit (#75388)
git bisect bad 0544c781728a665806b069cb8202acd4f6981a0a
# bad: [7bc6c4abe8e8d8ab70e02e4c2025a94dda01d908] [mlir][print]Add functions for printing memref f16/bf16/i16 (#75094)
git bisect bad 7bc6c4abe8e8d8ab70e02e4c2025a94dda01d908
# bad: [ec92d74a0ef89b9dd46aee6ec8aca6bfd3c66a54] Reland [X86] Respect code models more when determining if a global reference can fit in 32 bits (#75386)
git bisect bad ec92d74a0ef89b9dd46aee6ec8aca6bfd3c66a54
# good: [f976719fb2cb23364957e5993f7fc3684ee15391] Revert "[ADT][StringMap] Add ability to precompute and reuse the string hash"
git bisect good f976719fb2cb23364957e5993f7fc3684ee15391
# first bad commit: [ec92d74a0ef89b9dd46aee6ec8aca6bfd3c66a54] Reland [X86] Respect code models more when determining if a global reference can fit in 32 bits (#75386)

The text was updated successfully, but these errors were encountered:

nickdesaulniers · 2024-01-17T22:24:23Z

probably need to teach modpost what .ltext is (that it's llvm specific for the large code model) so that it doesn't walk off the end of a list and segfault (I bet). cc @aeubanks

aeubanks · 2024-01-17T22:27:58Z

.ltext is actually part of the ELF x86-64 psABI. It's basically just .text but also with the SHF_X86_64_LARGE section flag. It's useful for mixing small and large code model object files by distinguishing which functions are "large"/"far" and which ones are "small"/"near". So adding it to the list of allowed section names sgtm.

nickdesaulniers · 2024-01-17T22:29:27Z

Also, I'm curious if the UM build has been red since that LLVM commit from a few months ago?

nathanchance · 2024-01-17T22:31:14Z

probably need to teach modpost what .ltext is (that it's llvm specific for the large code model) so that it doesn't walk off the end of a list and segfault (I bet). cc @aeubanks

Will take a look.

Also, I'm curious if the UM build has been red since that LLVM commit from a few months ago?

Yes, I believe it has (at least from my quick survey). I think I missed it initially because of the whole counted_by fiasco that caused our clang-18 to be super red for over a month :/

nathanchance · 2024-01-18T00:17:16Z

So it turns out -no-pie was not getting added to the link flags because cc-option runs with -c but -no-pie is only used when linking ($(CC) is used for linking, #1715).

$ clang -Werror -no-pie -c -o /dev/null-x c /dev/null
clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument]

$ echo 'int main(void) { return 0; }' | clang -Werror -no-pie -o /dev/null -x c -

I think something like this would work, -no-pie is supported with all version of clang and GCC added support for it in 6.1.0 (https://gcc.gnu.org/git/?p=gcc.git;a=commit;h=428b381275bc95032274440f02d7719225de2c17, if I understand correctly):

diff --git a/arch/um/Makefile b/arch/um/Makefile
index 82f05f250634..34957dcb88b9 100644
--- a/arch/um/Makefile
+++ b/arch/um/Makefile
@@ -115,7 +115,9 @@ archprepare:
        $(Q)$(MAKE) $(build)=$(HOST_DIR)/um include/generated/user_constants.h

 LINK-$(CONFIG_LD_SCRIPT_STATIC) += -static
-LINK-$(CONFIG_LD_SCRIPT_DYN) += $(call cc-option, -no-pie)
+ifdef CONFIG_LD_SCRIPT_DYN
+LINK-$(call gcc-min-version, 60100)$(CONFIG_CC_IS_CLANG) += -no-pie
+endif
 LINK-$(CONFIG_LD_SCRIPT_DYN_RPATH) += -Wl,-rpath,/lib

 CFLAGS_NO_HARDENING := $(call cc-option, -fno-PIC,) $(call cc-option, -fno-pic,) \

$ boot-uml.py -k linux
...
Linux version 6.7.0-dirty ([email protected]) (ClangBuiltLinux clang version 18.0.0git (https://github.com/llvm/llvm-project b6f922fbf5e983122271aa12acb33f6172046d4d), ClangBuiltLinux LLD 18.0.0) #1 Wed Jan 17 16:53:21 MST 2024
...

$ boot-uml.py -k linux-stable-6.1
...
Linux version 6.1.73-dirty ([email protected]) (ClangBuiltLinux clang version 18.0.0git (https://github.com/llvm/llvm-project b6f922fbf5e983122271aa12acb33f6172046d4d), ClangBuiltLinux LLD 18.0.0) #1 Wed Jan 17 16:55:27 MST 2024
...

The warnings are fixed with the diff I have in #1981 (although I am getting a warning when I apply that diff to 6.1...).

I think this has implications for some of the errors David reported in #1715, I will comment there.

nathanchance · 2024-01-23T23:02:06Z

Patch submitted: https://lore.kernel.org/[email protected]/

The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null-x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux#1982 Signed-off-by: Nathan Chancellor <[email protected]>

Link: ClangBuiltLinux/linux#1981 Link: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]>

nathanchance · 2024-01-27T18:09:41Z

Accepted: https://git.kernel.org/masahiroy/linux-kbuild/c/846cfbeed09b45d985079a9173cf390cc053715b

The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]>

nathanchance · 2024-02-06T17:54:52Z

Merged into mainline: https://git.kernel.org/linus/846cfbeed09b45d985079a9173cf390cc053715b

This patch has Cc: [email protected] on it, so it will be backported automatically in time.

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]>

[ Upstream commit 846cfbe ] The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Sasha Levin <[email protected]>

BugLink: https://bugs.launchpad.net/bugs/2061814 commit 846cfbe upstream. The kernel builds with -fno-PIE, so commit 883354a ("um: link vmlinux with -no-pie") added the compiler linker flag '-no-pie' via cc-option because '-no-pie' was only supported in GCC 6.1.0 and newer. While this works for GCC, this does not work for clang because cc-option uses '-c', which stops the pipeline right before linking, so '-no-pie' is unconsumed and clang warns, causing cc-option to fail just as it would if the option was entirely unsupported: $ clang -Werror -no-pie -c -o /dev/null -x c /dev/null clang-16: error: argument unused during compilation: '-no-pie' [-Werror,-Wunused-command-line-argument] A recent version of clang exposes this because it generates a relocation under '-mcmodel=large' that is not supported in PIE mode: /usr/sbin/ld: init/main.o: relocation R_X86_64_32 against symbol `saved_command_line' can not be used when making a PIE object; recompile with -fPIE /usr/sbin/ld: failed to set dynamic section sizes: bad value clang: error: linker command failed with exit code 1 (use -v to see invocation) Remove the cc-option check altogether. It is wasteful to invoke the compiler to check for '-no-pie' because only one supported compiler version does not support it, GCC 5.x (as it is supported with the minimum version of clang and GCC 6.1.0+). Use a combination of the gcc-min-version macro and CONFIG_CC_IS_CLANG to unconditionally add '-no-pie' with CONFIG_LD_SCRIPT_DYN=y, so that it is enabled with all compilers that support this. Furthermore, using gcc-min-version can help turn this back into LINK-$(CONFIG_LD_SCRIPT_DYN) += -no-pie when the minimum version of GCC is bumped past 6.1.0. Cc: [email protected] Closes: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Masahiro Yamada <[email protected]> Signed-off-by: Nathan Chancellor <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> Signed-off-by: Portia Stephens <[email protected]> Signed-off-by: Roxana Nicolescu <[email protected]>

nathanchance added the [BUG] Untriaged Something isn't working label Jan 17, 2024

nickdesaulniers mentioned this issue Jan 17, 2024

Segmentation fault in modpost when building UML on mainline after LLVM commit 4bf8a688956a #1981

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nathanchance mentioned this issue Jan 18, 2024

hermiticity issues with ARCH=um #1715

Open

nathanchance added [BUG] linux A bug that should be fixed in the mainline kernel. [PATCH] Exists There is a patch that fixes this issue and removed [BUG] Untriaged Something isn't working labels Jan 20, 2024

nathanchance added [PATCH] Submitted A patch has been submitted for review and removed [PATCH] Exists There is a patch that fixes this issue labels Jan 23, 2024

nathanchance self-assigned this Jan 23, 2024

nathanchance added a commit to nathanchance/continuous-integration2 that referenced this issue Jan 25, 2024

patches: Add fixes for clang-18 UML regressions

8adc52b

Link: ClangBuiltLinux/linux#1981 Link: ClangBuiltLinux/linux#1982 Signed-off-by: Nathan Chancellor <[email protected]>

nathanchance added [PATCH] Accepted A submitted patch has been accepted upstream and removed [PATCH] Submitted A patch has been submitted for review labels Jan 27, 2024

nathanchance closed this as completed Feb 6, 2024

nathanchance added [FIXED][LINUX] 6.8 This bug was fixed in Linux 6.8 and removed [PATCH] Accepted A submitted patch has been accepted upstream labels Feb 6, 2024

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Link failure when building UML on linux-6.1.y after LLVM commit ec92d74a0ef89 #1982

Link failure when building UML on linux-6.1.y after LLVM commit ec92d74a0ef89 #1982

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Link failure when building UML on linux-6.1.y after LLVM commit ec92d74a0ef89 #1982

Link failure when building UML on linux-6.1.y after LLVM commit ec92d74a0ef89 #1982

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